The aims of the proposed research are two-fold: to determine the electron distribution in the vicinity of the nitrogen atoms in molecules of biologic interest and to correlate this data with other physical data and with measures of metabolic and biologic activity. The investigation will use the technique of nuclear quadrupole resonance (NQR) to measure the quadrupole coupling constants and asymmetry parameters of the nitrogen atoms in molecular solids. These two quantities can be interpreted in terms of the electron densities in sigma and pi bonding orbitals of the nitrogen atoms. They might also be correlated with chemical rates of hydrolysis, measures of carcinogenic activity, tumor-inhibiting ability, and other properties. The essential importance of learning about the electron charge distributions in such molecules is emphasized. Nearly all compounds of importance in biology, biochemistry, and pharmacology contain nitrogen, and the role of the nitrogen atoms must be fundamental. There are very few experiments currently feasible to determine the localized densities of sigma, pi, and lone pair electrons or to measure other properties of their wave functions in the ground state. Although the interpretation of NQR data is still elementary, it is a valuable means of checking the accuracy of theoretical calculations and correlating physical properties with biological properties.